bridge broken in -current?

If I do this:
ifconfig bge0 10.0.0.230/24
ping 10.0.0.1
All works as expected.
But when I do this:
ifconfig bge0 10.0.0.230/24
brconfig bridge0 create
brconfig bridge0 add bge0
brconfig bge0 up
I can't ping. In fact, no packets at all flow out bge0, tcpdump says;
though the bridge code seems to be filling its address cache from
somewhere.
Note there's only one interface in the bridge -- but this is the normal
case for e.g. a Xen dom0 before it brings up any of its domUs.
What's up?
--
Thor Lancelot Simon
Coyote Point Systems, Inc. <tls%coyotepoint.com@localhost>
Millerton, NY, USA